CVE-2026-68151: binfmt_elf_fdpic: only honour the first PT_INTERP

CVE-2026-68151: binfmt_elf_fdpic: only honour the first PT_INTERP

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

binfmt_elf_fdpic: only honour the first PT_INTERP

The program header scan handles PT_INTERP from a switch nested in the
scan loop, so its break leaves the switch and not the loop. A binary
carrying more than one PT_INTERP runs the case again and overwrites both
interpreter_name and interpreter. The previous name allocation leaks and
so does the previous interpreter reference, along with the write denial
open_exec() took on it. The denial is never released, so the file stays
unwritable for as long as the system runs.

An unprivileged caller reaches this with a crafted binary and repeats it
at will. binfmt_elf stops at the first PT_INTERP. Do the same here.

The flaw dates back to the driver's introduction in the pre-git history
tree introduced in v2.6.11 by 91808d6ebe39 ("[PATCH] FRV: Add FDPIC ELF
binary format driver").

The Linux kernel CVE team has assigned CVE-2026-68151 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.148 with commit e4563e07ef5c938d5332c5c44721db976f214bc6
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.101 with commit 21eaf5594a33d16343a011c752624099c30e918f
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.42 with commit 89b9121c3b0162655fc2f190b714ae64f1aa8cae
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.6 with commit 69ecc199880bf7e8d06224c82dc411d18f9285f8
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc5 with commit 3349ef6a366a61d631f6a263d12cea240957719d

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-68151
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/binfmt_elf_fdpic.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e4563e07ef5c938d5332c5c44721db976f214bc6
	https://git.kernel.org/stable/c/21eaf5594a33d16343a011c752624099c30e918f
	https://git.kernel.org/stable/c/89b9121c3b0162655fc2f190b714ae64f1aa8cae
	https://git.kernel.org/stable/c/69ecc199880bf7e8d06224c82dc411d18f9285f8
	https://git.kernel.org/stable/c/3349ef6a366a61d631f6a263d12cea240957719d